384 



BULLETIN OF THE BUREAU OF FISHERIES 



zenithicus comprises 79 to 99 per cent of all the Leucichthys taken by the special nets, 

 except in Thunder Bay and vicinity (records 20 to 24), where reighardi is common- 

 est. Zenithicus does not now support, nor is it certain that it ever has maintained, a 

 fishing industry, although at Marquette and Duluth lifts of the species are made 

 occasionally at certain seasons. In abundance it now ranks only second to artedi, 

 nigripinnis cyanopterus having ceased long since to occur in commercial quantities. 



BREEDING HABITS 



No specimens were taken in the spawning season, and the time of breeding and 

 the location of spawning grounds are known only from the testimony of fishermen and 

 from specimens taken out of Marquette, Mich., in December, 1922. Mr. Parker 

 informs me that by setting 10 miles N. by W. }/i W. in 20 to 40 fathoms during the 

 last week in November, from 3 to 6,000 pounds of spawning chubs usually are taken 

 in a gang of 2%-inch nets 5 miles long lifted after four nights (record 9). The 

 run is said to last about a week. The bottom on the spawning grounds is clay. Of 

 the five species of "chubs" that are known from Superior, Tciyi and hoyi never attain 

 sufficient size to gill in 2%-inch nets, reighardi is not known to occur east of Keweenaw 

 Point, Mich., and cyanopterus spawns in September; therefore these fish can only be 

 zenithicus. James Scott, of Grand Marais, Minn., gives information that indicates 

 that the species may spawn during November along the shores near Grand Marais. 

 He says that when the herring nets, which are floated to take artedi, fall by accident 

 to the bottom, zenithicus are taken in them in unusual abundance. The fish are 

 distinguished from the herring by the Grand Marais fishermen and are known 

 locally as ciscoes. 



Observations made on the state of development of the ovaries tend to confirm 

 the above-mentioned statements. Of the specimens taken at all ports during June, 

 July, August, and September, only a few specimens (and these were less than 200' 

 millimeters long) collected in Whitefish Bay on June 14, 1922 (record 1), showed 

 spawn in a state approaching ripeness. Those taken at Grand Marais, Minn., on 

 September 14, 1921, in Thunder Bay on September 19, 1923, and at Rossport, 

 Ontario, on October 4, 1921, had well-developed eggs, and an occasional male taken 

 on the last two dates showed traces of pearls. The female fish taken at Marquette, 

 Mich., in early December, 1922, were either spawning or ready to spawn. 



Late November and early December is probably the spawning time for the species 

 throughout the lake. It is likely that the small fish with ripe ova taken in June were 

 spawning for the first time and may have retained their eggs beyond the normal time 

 of spawning. At any rate, the proportion of specimens with such abnormal ovaries 

 was insignificant, and there is no reason to believe that the species spawns more than 

 once a year. The known spawning grounds at Marquette are at depths of 20 to 40 

 fathoms on clay, and probably it will be found that spawning grounds in other areas 

 of the lake are similarly situated. 



